P1- motion, forces, energy (forces, moment, pressure)

Question 1

Define force

Answer 1

-push, pull or twist
-causes change in speed, direction, shape
-measured in Newtons

Question 2

Which type of quantity are forces

Answer 2

-vector, so needs arrow heads
-arrow size - magnitude of force
-arrow head - direction of force
-Always label your arrows magnitude

Question 3

name the 9 types of forces
-first 6 are contact force
-last 3 are non- contact forces

Answer 3

-friction
-applied
-compression
-normal (upthrust, buoyancy for in water)
-air/ water resistance
-tension
-electrical
-weight
-magnetic

Question 4

Name the 6 contact forces

Answer 4

-friction
-applied
-compression
-normal
-air/ water resistance
-tension

Question 5

Name the 3 non contact forces

Answer 5

-electrical
-weight
-magnetic

Question 6

When walking on the floor what forces magnitude are equal or not equal to each other

Answer 6

-normal = weight
-thrust is more than resisting force (friction and air resistance combined) because the person is able to move

Question 7

Why do we not sink into the floor or float

Answer 7

because normal force is equal to weight

Question 8

define friction

Answer 8

force that opposes one surface moving or tying to move past another (opposes motion)

Question 9

Name 2 types of friction

Answer 9

-static
-dynamic

Question 10

define static friction

Answer 10

force that keeps object at rest

Question 11

define dynamic friction

Answer 11

opposes sliding or rolling motion

Question 12

Which is bigger: static or dynamic friction

Answer 12

static friction

Question 13

Which friction is on a object at rest

Answer 13

static

Question 14

What are the effects of friction

Answer 14

-opposes motion
-creates heat

Question 15

what is resisting force

Answer 15

force opposing another force

Question 16

What is resultant force

Answer 16

a single force that replaces all individual forces acting on the object, and have the same effect

Question 17

How do you find the resultant force

Answer 17

-arrows in same direction = add the forces
-arrows in different direction = minus the forces and the greater force will the the resultant force in the greater force direction
-if minus becomes 0, the resultant force is 0 so stationary

Question 18

define Newton’s 1 law

Answer 18

An object will remain stationery ( at rest) or move in a constant (uniform) speed in a straight line unless a net resultant force acts on it

Question 19

define Inertia

Answer 19

an objects resistance to change in speed and its direction

Question 20

What is the relationship between Mass and Inertia

Answer 20

As mass increase, Inertia increases

Question 21

What is the effect of increased Inertia

Answer 21

greater Inertia, harder to move the object when stationary or change its speed or direction when moving

Question 22

What is the mass of a body

Answer 22

measure of Inertia

Question 23

State Newton’s 3 law

Answer 23

-for every action, there is an equal and opposite force on it
-forces always act in pairs

Question 24

Define balanced

Answer 24

forces in opposite directions with the same magnitude

Question 25

an object with a constant speed has what forces that are?

Answer 25

forward and backward forces that are balanced

Question 26

When will there be in unbalanced forces

Answer 26

acceleration

Question 27

define Newton's 2 law - symbols and words

Answer 27

force = mass x acceleration F = ma -Newtons -as forces increases, acceleration increases; mass is constant -as mass increases, acceleration decreases; force is constant

Question 28

What is Hooke's law

Answer 28

the extension of a spring is directly proportional to the force applied to it until it exceeds the limit of proportionality

Question 29

Define limit of proportionality

Answer 29

-the point beyond which the extension of an elastic object is no longer directly proportional to the force applied to it -(where it stop being proportional)

Question 30

What is the formula for spring extension - symbols and words

Answer 30

Force = spring constant x extension of spring F = kx -Applied Force = Newtons (N) -Spring constant = Newtons per meter (Nm^-1) -extension = meters (m)

Question 31

what is the relationship between the spring constant and the stiffness of the spring

Answer 31

as spring constant increases, stiffness of the spring increases

Question 32

formula for extension of a spring

Answer 32

stretched length - original length

Question 33

define spring constant measure

Answer 33

stiffness of the spring

Question 34

When happens when: -a force is applied to a spring -the forces is removed from the spring -keep applying a force on the spring -stretch the spring too far

Answer 34

-change shape -return to original shape -keep getting bigger -spring expands to a point where it cannot return back to its original shape

Question 35

what are the 2 purposes for springs

Answer 35

-tension -compression

Question 36

define elastic object & examples

Answer 36

-an object that returns back to its original shape -rubber band, spring , sponge

Question 37

Give 2 places tension & compression springs are used -first 2 are tension -last 2 are compression

Answer 37

-machines -trampolines -pens -cell phones

Question 38

Principle of moment

Answer 38

anti clockwise moment = clockwise moment

Question 39

define moment

Answer 39

turning force

Question 40

which 2 direction can a moment turn to

Answer 40

-clockwise, -anti-clockwise

Question 41

Explain the resultant force in a moment

Answer 41

-difference between clockwise and anti-clockwise moments -needs to have a magnitude and direction (unbalanced)

Question 42

define Equilibrium in a moment

Answer 42

the clockwise and anti-clockwise moments are equal (balanced) = resultant force and resultant moment are 0

Question 43

define pivot

Answer 43

turning point (needs to touch the surface)

Question 44

Define distance in moment

Answer 44

distance has to be perpendicular to pivot from the force

Question 45

formula for moment - symbols and words

Answer 45

moment = force x perpendicular distance from the pivot m = Fd -Nm (Newton x meters)

Question 46

Define center of gravity

Answer 46

point where whole weight of object seems to act

Question 47

define a regular shape

Answer 47

has 1 or more lines of symmetry

Question 48

How do you find centre of gravity for regular shapes

Answer 48

do lines of symmetry and the middle where the lines intersect is the center of gravity

Question 49

How do you find center of gravity for irregular shapes

Answer 49

-on a retort stand place the cork -poke a hold into the shape and place it hanging freely using a nail -place a bob on the cork and draw a line on following the string of the bob on the shape. Repeat 3 time, each time poking holes in different places

Question 50

How is an object stable

Answer 50

the center of gravity is within the base of the object

Question 51

define stability

Answer 51

how likely an object will fall when disturbed

Question 52

relationship between the base and stability

Answer 52

-bigger the base, more stability

Question 53

relationship btw center of gravity and stability

Answer 53

-higher center of gravity, less stability

Question 54

Name 3 types of equilibrium and explain them

Answer 54

-stable equilibrium - object returns to its original equilibrium position -unstable equilibrium- object does not return to its original equilibrium position -Neutral equilibrium - object remains in displaced position

Question 55

what is pressure

Answer 55

force per unit area

Question 56

what is the equation for pressure in solid

Answer 56

p = F / A pressure = force / area - Pa (pascal) / Nm ^-2 F= N A = m^2 -10000cm ^2 = 1m ^2

Question 57

what is the equation for pressure in liquids

Answer 57

p = pgh pressure = density x gravity height

Question 58

how does pressure act in liquids

Answer 58

equally in all directions

Question 59

what does pressure not depend on

Answer 59

size and shape of the container